As discussed by Pedersen, Feline Practice May 1977, 13-14, feline infectious peritonitis (FIP) virus infection is very widespread in cats, with approximately 25% of normal urban cats having experienced the infection. The infection rate is even higher in catteries and multiple cat households, approaching 100% in many. These asympotmatic cats have antibody titers, with some apparently being immune to the disease, while others are apparently chronic carriers of the disease.
It is theorized that following infection with FIP virus, cats undergo some sort of primary illness, usually a mild respiratory disease which has not yet been defined fully. Following this primary infection most cats apparently recover. A proportion of these cats, however, will become chronically infected. Some of these chronically infected cats will remain asymptomatic, while others will develop serositis or granulomatous disease (effusive or non-effusive FIP) over a period of time. (See also Pedersen Feline Practice May 1976, 42-51).
Recently a new test for antibodies to FIP virus (Pedersen, Amer. J. Vet. Res., 37, 1449-1453, 1976) makes possible a more effective study of the epidemiology and pathogenesis of the disease.
One major drawback in the study of FIP virus has been the failure to find a method adapted to large-scale in vitro cultivation of the FIP virus. Large-scale in vitro production of the virus is useful in studying the virus, its structure, antibody and drug responses, and as well as the epidemiology and pathogenesis of the disease. Also such in vitro virus production would make possible the economical production of a virus based FIP vaccine.
Heretofore, attempts to replicate FIP virus in vitro have been unsuccessful. Pedersen, Amer. J. Vet. Res., 37, 567-571, 1976, has described the replication of FIP virus in autochthonous peritoneal cell cultures, but acknowledges that this technique falls short of a reasonable virus production method. (See also Ward et al, Amer. J. Vet. Res., 35, 1271-1275, 1975).
FIP virus has been characterized as being a virus similar in size morphology and budding characteristics to members of the coronavirus group. (Pedersen, Amer. J. Vet. Res., 37, 1449-1453, 1976; Starks et al Amer. J. Vet. Res., 37, 335-338, 1976.)
Cook et al, Archives of Virology, 50, 109-118 (1976) describe the use of chicken trachial organ cultures for the replication of avian infectious bronchitis virus.
Stott et al, Veterinary Microbiology, 1, 65-69 (1976) describe the replication of a bovine coronavirus in organ cultures of fetal trachea.
Cook et al, Research in Vet. Sci., 20, 348-349 (1976) describe the propagation of several strains of avian infectious bronchitis virus in trachial organ cultures.